Texture segmentation based on fractal attributes using convex functional minimization with generalized Stein formalism for automated regularization parameter selection

Barbara Pascal
CRIStAL (SIGMA team), Lille
http://perso.ens-lyon.fr/barbara.pascal/

Date(s) : 27/11/2020   iCal
14 h 30 min - 15 h 30 min

Texture segmentation still constitutes an ongoing challenge, especially when processing large-size real world images. The aim of this work is twofold.
First, we provide a variational model for simultaneously extracting and regularizing local texture features, such as local regularity and local variance. For this purpose, a scale-free wavelet-based model, penalized by a Total Variation regularizer, is embeddedinto a convex optimisation framework. The resulting functional is shown to be strongly-convex, leading to a fast minimization scheme.
Second, we investigate Stein-like strategies for the selection of regularization parameters. A generalized Stein estimator of the quadratic risk is built. Then it is minimized via a quasi-Newton algorithm relying on a proposed generalized estimator of the gradientof the risk with respect to hyperparameters, leading to an automated and data-driven tuning of regularization parameters.
The overall procedure is illustrated on multiphasic flow images, analyzed as part of a long-term collaboration with physicists from the Laboratoire de Physique of ENS Lyon.


Slides: https://www.i2m.univ-amu.fr/seminaires_signal_apprentissage/Slides/2020_11_27_B_Pascal_Marseille20.pdf

Emplacement
Site Nord, CMI, Salle de Séminaire R164 (1er étage)

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